Startup problem

Recently, when I switched on my Windows 7 desktop, the fan was noisy and after several minutes the screen was still blank. I pressed the button on the system box to switch off and then on again ten seconds later. This time the fan was quiet as usual and the boot-up proceeded normally with the "desktop" appearing on the screen. Any idea what caused the problem and does it indicate that something is about to fail - the computer is out of warranty.

FAN
Are we talking about a case fan or a CPU-heatsink fan?
(fans wear, connections come loose, even a CPU heatsink can be knocked loose)
Was it just that one time or are you looking at a pattern?
(if it's a one off I wouldn't worry so much, if it's a pattern I'd be opening the case and taking a real good look)

Keep an ear, and an eye on it.

DRIVE IMAGINGInvest a little time and energy in a well thought out BACKUP regimen and you will have minimal down time, and headache.

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It sounded like the power supply fan, which is normally very quiet - this time the noise was quiet obvious but still sounding like a fan, without any rattle or other noise. I do not know if the computer booted up because there was no signal being sent to the monitor - the screen remained black. I switched off and then on again, this time it booted normally with no apparent fan noise, as usual. It has not happened again.

One other possibility is a graphics card fan. I ran into one PC that wouldn't boot becuase the graphics card overheated. It also sounds like a good time to open up the case and blow out all the accumulated dust with a can of compressed air.

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Anthother possibility is that it could have been a failed BIOS entry (don't ask me how), not a failed BIOS flash, that's something completely different.
This may not really be related to your situation in any way, but just something that can happen that I would consider weird behavior.

Some BIOS brands are notorious for huffing and puffing with alternating fan speeds when something is amis...even a minor BIOS hiccup.
It doesn't neccessarily mean something is broken, or about to break, just a freak occurance that can happen from time to time.
A hard power off and restart may resolve it, but I know first hand that Intel BIOS's are infamous for doing that on occasion.

DRIVE IMAGINGInvest a little time and energy in a well thought out BACKUP regimen and you will have minimal down time, and headache.

Yes, I too think it's the last, as the BIOS kicks in it controls the heat sink fan speed, if it doesn't kick in, no picture, no boot, no fan speed control so it runs full speed and sounds much louder than normal. From experience, it can be a freak occurrence, especially if the system was just moved for any reason or it can also mean the power supply is getting a bit weak or once in a great while, a sign the motherboard is getting a bit flaky.

I've had Dell's do this, the fan jumps up to top speed so it sounds a little like a hair dryer, or jet fan. Sometimes indicates the computer is on it's way out. Don't know if it will help but you could try taking the heat sink off the CPU and replace the cooling/insulating paste that helps with heat transfer.

From a cold start, other than in a catastrophic case fan failure that shuts down the PSU, problems with the case fan would be very unlikely to stop the system from starting to the BIOS screen at the very least. I’m writing this on a 4 core 3.5ghz with 3xHDs, which has been on for 10 hours flat on a reasonably warm day, and the CPU is the highest component temperature at 41C – and I ain’t got the case fan on!

The exception to the above would be in designs such as Dell where they sometimes have a ducted, combined case/heatsink fan in the front of the case. If that fan was playing up the whole thing could go into crisis. Good old Dell, eh?

Failure of the CPU fan would cause the CPU thermal overload protection to cut in and shut down the CPU, but as you say the fan was running loudly it is unlikely to be that – unless the fan has structurally failed in some way and was just making a noise and not actually going around. Degradation of the thermal compound between CPU and heatsink is unusual, but I have seen it, and again that could account for CPU thermal shutdown and the CPU fan running full tilt to try to cool it down. But why would it not do the same thing again on the next restart?

A graphics card fan failure would be unlikely to shut everything down before it even gets to the BIOS screen – at that stage it ain’t done anything yet to cause it to heat up.

Are you sure it was a fan making the noise and not a disk inadvertently left in the optical drive trying to boot? If the BIOS boot order is set to Optical first, followed by HD, a disk with no autoboot file can often wind itself right up – I’ve had such systems in the shop that just boot to a blank screen (because the BIOS doesn’t know what to do next, but I would still expect it to boot to the BIOS screen first.

A failed or failing RAM stick (or a dirty RAM connector) sometimes shows up as a blank screen without going to the BIOS screen, so that is definitely a contender for the fault symptoms – but why the fan speed. A serious RAM fault telling the mobo sensing circuit that it is overheating? - never experienced or heard of it but I suppose it’s feasible.

If/when the fault occurs again, I guess the first thing to try is take the heatsink fan off and vacuum all the junk out of the heatsink and the case in general. Remember to switch off and discharge any static from yourself before working on the internals. Then click out the memory sticks and press them back into the slots to clean them – you can also use isoprop to clean the stick contacts if you wish but be careful. You could also pull out and push back the main PSU to mobo connections to clean their contacts - but do it gently. If you feel the case fan may be suspect then temporarily disconnect it – most case/fan air routing designs are so ill-conceived that all of the fans end up working against each other anyway! (rant over - in a former life I was a professional ventilation systems designer)
Next try it with one or the other RAM stick out, and also in different slots – it only takes 1 dud stick to shut the whole thing down.
Reseating the heatsink on the CPU with some fresh, good quality heat transfer compound would be next favourite but take it gently – the suction/adhesion of the old compound between heatsink and CPU can have you pulling the CPU pins straight out of the ZIF socket before you know what you've done – to be avoided.

Hope the above may help.

Cheers, Chris

Remember rule #1: If it ain't broke, don't fix it!

Industrial electrical engineer, running a system building/repair business in Cornwall UK, for the last 15 years.

Built my first computer in 1978 - in the days when you had to hand-solder in all the components and 16k RAM was considered extravagant!

Fans do fail after a few years. Replacement fans are cheap. So just keep an eye (or ear) on the situation.

Desktop computers should be internally dusted every 6 months or so, or dust can eventually causing overheating problems as well as impeding fans rotation, and creating a fire risk as all that dust could be set on fire.